1. Field of the Invention
The present invention relates to a lens shift device for a photographic printer, in which printing lenses are changeable by moving a printing lens into and out of a printing light path.
2. Description of the Related Art
A photographic printer is known from Japanese Laid-open Patent Application No. 2-278248 (corresponding to U.S. Pat. No. 5,006,886), wherein a zoom lens is utilized for printing so as to make prints of a predetermined size from photographic films of relatively small sizes, such as 110 film and 135 film. This is accomplished by changing the focal length of the zoom lens in accordance with the film frame size. On the other hand, when making prints from a film having relatively large frames, such as 120 film, a corresponding fixed focus lens is set in the printing light path in place of the zoom lens.
Generally, printing of full size frames of 135 film (35 mm in width) is required most frequently. For this reason, a lens changing system has been suggested, wherein a zoom lens for printing small size frames is ordinarily mounted in a photographic printer, and when printing 120 film, the zoom lens is removed from a lens deck into a rest position. In its place, a fixed focus lens specific to 120 size is placed in the lens deck.
For example, Japanese Laid-open Utility Model Application No. 1-130108 discloses a printing lens positioning device with a link arm. The link arm consists of a couple of arm portions linked at one end to each other. One end of the link arm is pivotally mounted to a lens deck, whereas the other end of the link arm is mounted to a lens board. A printing lens is mounted on the lens board, such that the printing lens is movable between a lens set position and a rest position by pivoting the link arm.
In the above-described conventional printing lens positioning device, the movable range of the lens board is so wide that it is necessary, for fitting the lens board to the lens deck, not only to orient the lens board to the lens deck, but also to position the lens board properly. Therefore, changing the printing lenses in this conventional device is somewhat cumbersome and laborious. Moreover, the link arm needs a large amount of space for movement.